My perspective is you should listen to what your users say, but treat that as just one piece of input into what you do.
Ie, rather than this:
what we do = what users tell us
It should be:
what we do = f(what users tell us, x)
Where f is your own thinking, and x is other sources of useful data.
My feeling is that "vision" and "data" aren't in conflict -- you should attempt to integrate data into an over-riding vision, but you should be prepared to ditch or tweak the vision if it becomes too detached from reality.
I could write a lot more about this -- I think the problem goes a bit deeper than "faster horse" dynamics that some people have mentioned. The whole lean startup, listen to your customers thing is supposed to be about applying the scientific method to founding companies.
Trying out random things and recording the results might be "experimenting" in the normal sense, but it's not the scientific meaning of experimenting. You should concoct a theory and work out what you need to look for before you start looking. The Lean Startup book itself goes into a lot of depth about which metrics to track, how different marketing models require different metrics, etc (everyone thinks they know "lean concepts" because they read a few blog posts but the book goes into way more depth).